Phonograph tone arm control



Dec- 21, 1954 H. H. vANDERzEE ETAL 2,697,608

PHONOGAPH TONE ARM CONTROL Original Filed oct. 21, 194e 2 snets-'sneet 1DC- 21, 1954 H. H. vANDERzEE Erm. 2,697,608

PHoNoGRAPx-x TONE ARM coNTRoL original Filed o ct. 21. 1946 2sneezs-sn'eet 2 Il lllll lllll llllllll United States Patent OPHONOGRAPH TONE ARM CONTROL Harry Herbert Vanderzee, Grand Rapids,Mich., and Robert A. McCallum, Clarendon Hills, Ill., assignors, bymesne assignments, to AMI Incorporated, a corporation of DelawareApplication January 26, 1951, Serial No. 207,952

6 Claims. (Cl. 274-15) This invention relates to automatic phonographs,and the present specication is a division of our copending applicationSer. No. 704,588, filed October 21, 1946.

In the automatic phonograph art, it is customary to provide a magazinefor a plurality of phonograph records, with a selector and transfermechanism so arranged as to select any one of the records of themagazine and place it in playing position on the turntable. The tone armis then automatically positioned on the record to begin the playingcycle. When the play is completed, the tone arm is lifted from therecord and swung outwardly to a position well beyond the marginal edgeof the record I and clear of the turntable, so that the transfermechanism f may remove the record and replace it with another selection.

It is desirable in machines of this general type to provide the tone armwith operating means so designed as to place the arm on the record witha considerable degree of precision, so that the playing stylus willimmediately engage the rst groove of a record and will thereafter becarried across the record surface by the spiral groove. To permit freemovement of the arm, it is desirable that the arm shall be freelypivoted and unrestrained as the playing of the record progresses, sothat it may follow the groove faithfully.

The present applicants have learned, however, that there are certainshortcomings in the tone arm control mechanisms of the prior art whichpreclude satisfactory operation under certain conditions of operation.For one thing, it has been learned that while freedom of the movement ofthe arm in traversing the record is essential, yet this freedom ofmovement may result in erratic performance if the mounting of themachine is not exactly level, since it unbalances the arm and permitsgravity to impart unwanted swinging motion to it. Obviously, this maycause the tone arm to swing inwardly prior to engagement with the recordin such a manner as to place the stylus of the tone arm on the record ata point other than the proper starting groove, or even to drag thestylus laterally across the grooves in such a manner as to scratch therecord and damage the stylus. Nevertheless, it has heretofore beendeemed impossible to restrain the tone arm against inward movement atthe moment the stylus engages the record groove without bringing aboutother operating difficulties, since any positive restraint on the armwould prevent the stylus from following the spiral track of the grooveand would cause the stylus to jump from one groove to thenext, resultingin serious damage to the record, the stylus, or both.

It is, therefore, the primary object of the present invention to providea tone arm control assembly including means to stabilize the arm at themoment the stylus contacts the record in such a manner that the stylusis not free for uncontrolled swinging in response to external forces,yet can follow the spiral groove of the record. More specilcally, it isone of the objects of the invention to provide a tone arm control whichis eiective to automatically lift a phonograph tone arm, move itinwardly over the edge of a record, and lower it at the precise positionof the first record groove, wherein the several coacting parts are sorelated to each other as to provide a positive means for holding thetone arm clear of the turntable as the record is placed thereon orremoved therefrom, and to exert a yielding resilient restraint on thetone arm as the stylus engages the record groove. This restraint issutlicient to permit the stylus and tone arm to follow the spiral grooveof the record from the rst instant of engagement therewith, yet toprevent unwanted swinging of the arm before its engagement with therecord. Thus the tone arm and stylus are stabilized and protected fromundesired gravitational inlluences, even in cases where the mounting ofthe mechanism is not entirely level.

It is a further object of the invention to provide a tone arm controlmechanism having the functional characteristics outlined above, whereinall of the desired functions are accomplished by a single compound camhaving a plurality of coacting cam surfaces to control the severalfunctions of the tone arm.

A still further object of the invention is the provision of a tone armstabilizing and control device wherein the tone arm is restrainedagainst movement in either direction at the instant the stylus engagesthe record, but in which the arm is positively restrained againstoutward movement and is restrained against inward movement by acomparatively light, yieldable spring, so that the stylus of the arm mayfollow the first few grooves of the record without compressing thespring suliiciently to interfere with the proper tracking of the stylusin the groove.

A still further object of the invention is to provide a tone arm controlmechanism as indicated above, wherein the entire mechanism is capable ofaccomplishing the functions rapidly and with a high degree or'precision, yet wherein the individual parts of the tone arm mounting andcontrol assembly are relatively rugged and sturdy, so that the entiremechanism is well suited to automatic phonograph installations in whichthe mechanisms are often subjected to considerable rough treatment andabuse.

A preferred embodiment of the teachings of this invention is illustratedin the drawings herein, in which:

Figure l is a fragmental plan view of a phonograph turntable recordtransfer mechanism and tone arm as employed herein. The completephonograph is more fully illustrated in the parent case Ser. No.704,588, of which this specification is a division.

Figure 2 is an elevational view of the mechanism illustrated in Figurel, with parts of the tone arm broken away to show the pivotal supportthereof.

Figure 3 is a detail plan sectional view taken substantially on theplane of the line 3-3 of Figure 2, and showing the configuration of thecompound control cam employed herein.

Figure 4 is a perspective view of this cam.

Figures 5, 6 and 7 are fragmental views similar to Figure 2 but showingthe several parts of the mechanism in the positions they assume atvarious phases of the operation of the device; and

Figures 8, 9 and 10 are plan sectional views taken on the planes of theline 8--8 of Figure 5, 9-9 of Figure 6, and 10-10 of Figure 7, showingthe relative positions which the control cam assumes during each of theseveral stages of operation of the mechanism.

As more fully disclosed in the aforementioned application Ser. No.704,588, the entire phonograph mechanism is mounted on a base plate 35(Figure 2) so that the transfer mechanism generally designated as 99 mayswing the transfer arm to take a record 40 from a magazine (not shown)and to deposit the record in playing position on a turntable 101. Theturntable 101 is driven by a motor 102 suitably mounted on the base 35,and a tone arm 103 is swingably mounted on the base and arranged to beplaced on the record surface by a control cam generally designated as104. The control cam 104 is carried on a projecting end of a shaft 347which forms a part of the record transfer mechanism 99 and projectsoutwardly therefrom. The details of the record transfer mechanism willnot be described in this specification, it being deemed sufficient topoint out that this mechanism is such that in the normal cycle ofoperation of the phonograph, the shaft 347 is oscillated back and forththrough an arc which is almost, but not quite, a complete revolution.That is, the shaft 347 and cam 104 (which are shown in their position ofrest in Figure 2) move in a clockwise direction for about 340,immediately after the record has been placed on the turntable. Thismotion causes the tone arm 103 to be lifted and placed on the turntablewith the stylus S in the first record groove 40h of the record. Afterplaying is completed, theshaft 347 and cam 104 move in acounterclockwise direction, returning the cam to its original position.This movement causes the cam to lift the tone arm and stylus from therecord and swing it outwardly lbeyond the outer marginal edge 40ctthereof (Figure l).

The tone arm 103 is mounted on an adjustable bracket 350 carried by acontrol varm `354 which is `in turn supported on a pivotal sleeve 355carried on a stud `356 lixed in the machine base 35, so that the entirearm assembly may be pivoted toward 'or away from the Vrecord and liftedfrom or placed on the record as required. All of these functions areperformed Vby the cam 104. The tone arm 103 is mounted on a pair of-pivot pins 348 which extend outwardly from 4the opposite arms of aU-shaped Ysupporting bracket 349, which is in turn secured to a verticalportion of the adjustable mountingfbra'cket v350 (Figure 2).The-downward -piovtal movement ofthe tone arm 103 on the bracket'islimited by a-stop screw -'3'51. The bracket 350 is secured to thecontrol arm -354 .by a pair of screws `352. One of Ytheselscrews extendsthrough -an elongated 4slot 353 in the bracket 350 (Figure 8), so ythatthe position -of the bracket Y350 on the arm 354 may vbe adjusted toplace -the-stylus S on the rst record groove with lexact precision.

The arm 354 is perm'anentl'yailxed to the upper 'end of -the verticalpivot sleeve 355, which is rotatable on the fixed stud 356 andvertically shiftable with respect thereto. The'flower end ofthe-stud356nisrigidly secured in -the base 135 of the machine. The'sleeve 3551isthus free to pivot on the stud'to -permitswinging Vmovement of -the-tone arm, and the -tube may slide vertically 'on Vthefstud as requiredlas the-tone arm-tis Alifted from the record surface `or replacedthereon. A screw 360 -extends through the arm 354 and engages the upperfend 'of th'e stud 356 to llim'it the downward movement of the tone armassembly.

The lower face of the `control arm 354 is positioned immediately abovethe cam 104 so that the outer :peripheral surface 362 Vof the cam willdirectly engage Lthe arm to `raise `or lower ythe tone farm as required.

The lower face of the arm 354`1sprovided with a pair of'camfollowenpins.358and359, whichar'evspaced apart 'from eachother tofengage the innercamlsurface 361 and the outer camlsurface -364.respectively, to-convtrol the swinging movements ofthe tonearm.

The general mode ofoperation of the tone 'arm Vis best'describedinconnection with-Figure l, wherein-the full line, broken line anddotted line views -of `the tone r arm 103 indicate the three principalpositions l'through which this armlfpassesduring its .cycle ofoperations. In operation, the tone-arm -1034swings from an outermostLposition wherein it lies on the center line A through a startingposition wherein it lies falong the center line B, andfthence to aninnermost position -along the Vcenter line C.

Broad1y1stat'ed,.it lis the tfunction of Athe cam 104 -tolhold the arm'103 -in lits fullline-position, where it is well clear of theturntable, yas'the lreco'rd 40-is-placedfin position bythe transfer arm120. The cam then-swings -the 4tone a'rm inwardly, placing the stylus -Son --the record at the precise location ofthe outermost :record `-groove40h, but restraining-the armpositively-fro'm outward displacement andexerting light yielding 'restraint 'onthe armfin such amanner astop'revent it from being 'accidentally "swung inwardly by inertia,vibration lor `gravitational intluences, but -to permit-the stylus tofolflow the spiral grooveofthe record from the instant of engagement.'record until it 'reachesa Eposition on the line C, with the stylus S-in the innermost groovef'40c`of therec'ord.

The 'arm is then left free toi'traverse the At this fpoint anautomatically -actuated 'switch (not shown) causeslthe cam 104Atofreturnto its original position, lifting-the tone arm from the record Vandmoving it positively outwardly until it lies on the'center line A.

-In this `position the tone arm -islat lrest vand is spacedsubstantially away fromrtheV marginal edge *40a of the record, so as toprovide ladequateclearance for movement of the transfer arm 1Z0 inlifting the record from 'the turntable 4and 'replacing it with'anotherrecord on which a differentl selection isrecorded.

The severalsuccessivesteps of operationof thetone farmarelillustr'ated'infFigui-esl, 5, 6 and 7 respectively, `with thefcorresp'onding #positions Iof lthe control ycam shown in Figures 3, 8,9 and 10. In Figure 2 the cam 104 lis in the position of rest which litoccupies when the tone arm lies on the center line A and is spaced fromthe record. At this time the downward sliding movement of the pivotsleeve 355 is limited by engagement of the stop screw`r360, with theupper end of the xed pivot stud 356, and while the point of the stylus Smay ylie slightly belowr the uppermost surface of a record` 40 on theturntable, the downward motion of the st-ylus is limited by fthe stopscrew 351'on the bracket 350. This lst'op `screw vengages Athe undersideCof the tone varm and llimits the, movement of the -arm 103 on thepivots 348. When in this position the ton'e arm is positively restrainedagainst swinging movement ineither directionl The-`uter :follower pin358 v(-Figure 3) engages the outer dat surface 364a to prevent inwardswinging of the arrn, while the "innermost follower pin 359 engages theinner flat face 361a of the cam to limit outward `swinging "of the toneiarm.

Rotation of `thecam i104 through an larc 'of substantially 340 in aclockwise direction lifts the tone arm above the surface of the, record,swings it inwardly until it lies on lthe ycenter line B as illustratedin ibroken lines `in Figure 1,'and rvlowers the 4arm gently to 'bring'the stylusS into engagement -with the record at the :precise locationof the `-rst lrecord groove`40b. The first Yportion -of vthis movementof -cam 104 .lifts the tone arm kand `rstylusxabo've the Vsurface of `arecord on the 'turntable, as shown yin -Figures 5 and `8. 4Asseen-inFigure 5, ethe outer peripheral-surface 362 of 'the cam 104engages the underside of the c'ontrol arm :354, and as the high point'363'of this `cam approaches 'the arm 354 it lifts the stylus S abovethe surface of the record-40. Theposition of the follower.-pins358and3591is not immediately changed, however, and 'the tone farm-therefore continues fto=occupy a position on the `center 4line 4A untilthe stylus is lifted vabove the recordfsu'rface.

The parts then move -to the positionsfof Figures 6 'and 9, wherein ,the=tone arm 4has lbeen swung `inwardly 'to a position lon the center line1B, and the stylus S has been lowered Vinto engagement with the flirstygroove 40h of the frecord. The -tone arm is moved inwardly by theoperation of the innermost cam ifollower ypin 359, which rides`inwardly-along theinclined I-cam :'sur- Vface -361b and onto the Ydwellportion 361e `of the cam. VAs this occurs, the outer/cam follower tpin358 Jleaves thefsurface 364i: Y-ancl overrides `.the `return bendAportion 368. of a leaf spring 366, `which fis 'mounted on the'cam104'by a pair of fmachine screws-367. Concurrently with this inwardmovement, :the rhigh lpoint 363ontherperipheral surface Y362 of the'eam104 passes Aunder thejpoint of contact'with the control farm =35'4 .andIlowers 'the 4tone arm assembly tobring thefstylu's S :into contactwithfthefuppermostfsurface yof fthe record.

:It will be understood, 4of course, that the fcontrolfarm -354isuloyvered sufficiently "tot'provide :slight clearance abovethelimit'screw 351-sojthat=the'tonearm may'have 'someipivotalimovemcnton the pivots 1348. The several .portions ofthe .car'n surfaces 4andtheir followers are 'so related ythat thefst'ylus -is-:placed inthefiirst :groove of -a nrecord with a vconsiderable#degree vofprecision, and so that it engages the record just lbefore `the-followerpin 358 leaves Ithe 'end of the return ibend-portion y368 ofltheleaf spring 366, This act'ion in'afyfbe 'adjusted with 'f'extremeaccuracy by r`shifting the adjusting bracket f350 lslightly 'withrespect to `the "c'otitrl arm 354, and securing it -in properly adjustedposition lthereon :by the 'two #screws 352.

In 'the'operation `of"-pl'aeing lthe stylus 'on the 'record, and yin theperiod lprior to actual engagement of "the "stylus -`with the r'e'c'ord4groove, the tone arm is lig'li'tl'y restrained L'against,inwardswinging 'movement by 'the 1forceeXer'ted byj'the leaf "spring 366. lThis "restalnt'is "notiso positive, however, las jto preventdhe "tonefarm 'from following Lthe` record groove ffr'om l' thefv'ery instant oflengagemer'it. "As soon Ias the v`'stylus -begins --to track in ythe:record zgroove thej restraint on a th'e arm is whll'y removed vbyitheIc`:onti1r n.ietjl rotation of the' cam l'10'4 from the positionjustdcscribedtothelpositions f"Figur"`es'7 -ad' 10.This'istlieiposition'whieh the ca'mfoccupiesas the :recordf is Iplayed,land las] `will bef s'een Afrom the location yot" partsj in the figure,the l inward 'rricvementl of l"the tone "arm as 'j it ltraverse@ fthe'record from the utermst l"groove1 40bt o the innermost groove 140C`wil'lcarry''the tone arm from tlie center `line B to the center 'lineC,

and will cause the inner cam follower 359 to move clear of the camsurfaces 361D and 361C. As this occurs, the outer cam follower pin 358will move into the olfset portion 365, but will stand clear of allcontact with the cam until the playing of the record is completed.

When the tone arm reaches thecenter line C, an automatic limit switchand motor (not shown) return the cam 104 to its original position byrotation in a counterclockwise direction as viewed in these drawings.The first action of the cam occurs when the high point 363 of theperipheral cam surface 362 engages the underside of the control arm 354and lifts the stylus S from the record surface. Continued rotation ofthe cam will cause the inclined portion 364d of the outer cam surface364 to engage the follower pin 35S and swing the tone arm outwardly froma position on the center line C to a position on the center line A.During this operation, the pin 358 rides under the free end of thereturn bend portion 368 of the leaf spring 366, and the parts return totheir original positions wherein they are ready for the next subsequentoperation.

From the above it will be seen that while the tone arm control mechanismshown here stabilizes the movement of the tone arm sufficiently toprevent uncontrolled swinging of the arm as it engages the record, yetthe restraint applied to the arm is nevertheless suiciently yielding sothat the arm may follow the spiral of the record groove at the instantof contact therewith.

These objects are accomplished, moreover, by a structure which is simplein construction and consists of a relatively few parts, each having theinherent ruggedness and strength to withstand long continued usage. Itfollows that by the present teaching it is feasible to overcome some ofthe principal defects in mechanisms heretofore designed for thispurpose, yet to do so with a simple, reliable, and comparativelyinexpensive mechanism.

Having thus described our invention, what we claim as new and desire tosecure by United States Letters Patent is:

1. In a phonograph having a turntable and a tone arm carrying a playingstylus engageable with a record on the turntable, the combination of atone arm mounting and control assembly consisting of a pivotal supportconstructed and arranged to swing in a plane parallel to the surface ofa record on the turntable, and a cam follower member carried by saidsupport with an adjustable bracket on said cam follower carrying thesaid tone arm; a compound tone arm positioning cam constructed andarranged to move said follower; said cam having one surface contactingsaid follower to raise the tone arm with respect to the record and lowerit thereon, with another cam surface coacting therewith to swing thetone arm inwardly over the edge of the record to the rst groove thereof,and a resilient spring coacting with said cam and engaging the followerwhile the tone arm is placed in the first groove of the record toprovide light resilient restraint against free inward movement of thetone arm until the stylus thereof is seated in the record groove.

2. In an automatic phonograph, a power actuated tone arm positioning andcontrol mechanism comprising, in combination, a Vertical pivot studhaving its lower end xedly secured to the phonograph frame, a relativelylong slender pivot tube in telescoping relation with said stud andadapted for pivotal and vertical sliding movement with respect thereto;a cam follower plate secured to the upper end of said pivot tube andprojecting in an outward horizontal direction therefrom; a rotatablecontrol cam disposed immediately below said cam follower plate andadapted to engage the under side thereof to intermittently elevate saidplate; and an adjustable screw extending through the cam follower plateto bear against the upper end of the aforementioned pivot stud to effectprecise vertical adjustment of the cam follower plate with respect tothe rotatable cam thereunder: a tone arm bracket disposed on the upperside of the cam follower plate and adjustably secured thereto, with anupright support portion of said bracket carrying a tone arm pivotedthereon, with an adjustable stop screw to engage the tone arm and limitits downward pivotal movement; together with a pair of cam follower pinsfixedly spaced apart from each other and projecting downwardly from theunderside of the cam follower plate and disposed on opposite sides ofthe rotatable control cam; said pins being adapted to alternativelyengage two opposite cam Surfaces on said control cam to swing said tonearm into a series of predetermined positions in timed sequence with theraising and lowering of said tone arm by engagenient of said cam withthe under side of the cam follower p ate.

3. In an automatic phonograph, a power actuated tone arm positioning andcontrol mechanism comprising, in combination, a pivoted cam followerplate projecting in an outward horizontal direction; a rotatable controlcam disposed immediately below said cam follower plate and adapted toengage the under side thereof to intermittently elevate said plate; atone arm bracket disposed on the upper side of the cam follower plateand adjustably secured thereto, with an upright support portion of saidbracket carrying a tone arm pivoted thereon; together with a pair of camfollower pins fixedly spaced apart from each other and projectingdownwardly from the under side of the cam follower plate and disposed onopposite sides of the rotatable control cam; said pins being adapted toalternatively engage two opposite cam surfaces on said control cam toswing said tone arm into a series of predetermined positions in timedsequence with the raising and lowering of said tone arm by engagement ofsaid cam with the under side of the cam follower plate.

4. In an automatic phonograph, a power actuated tone arm positioning andcontrol mechanism comprising, in combination, a vertical pivot studhaving its lower end iixedly secured to the phonograph frame, arelatively long slender pivot tube in telescoping relation with saidstud and adapted for pivotal and vertical sliding movement with respectthereto; a cam follower plate secured to the upper end of said pivottube and projecting in an outward horizontal direction therefrom; arotatable control cam disposed immediately below said cam follower plateand comprising plural cam surfaces adapted to swing said follower platebetween a plurality of angular positions and to engage the under sidethereof to intermittently elevate said plate; and an adjustable screwextending through the cam follower plate to bear against the upper endof the aforementioned pivot stud to effect precise vertical adjustmentof the cam follower plate with respect to the rotatable cam thereunder:a tone arm bracket disposed on the upper side of the cam follower plateand adjustably secured thereto, with an upright support portion of saidbracket carrying a tone arm pivoted thereon, with an adjustable stopscrew adapted to engage the tone arm and limit its downward pivotalmovement.

5. In an automatic phonograph having a power actuated tone arm, apositioning and control mechanism comprising, in combination, a controlcam consisting of a single rotatable wheel having one cam surface aroundits peripheral edge and a pair of additional coacting cam surfaces onits front and back faces respectively, with a single cam follower platemounted for movement in at least two planes, with said plate adapted tobe engaged by the peripheral edge of said wheel; a pair of cam followerpins xedly spaced apart from each other and mounted on said plate, anddisposed on opposite sides of the peripheralv edge of the control cam;said cam pins being adapted to alternatively engage the separate opposedcam surfaces on the front and back faces thereof; with mechanicalconnections between the follower plate and the tone arm to swing saidtone arm into predetermined angular positions by operation of said pinsin timed sequence with the raising and lowering of said tone arm byengagement of said cam with the cam follower plate.

6. In an automatic phonograph having a power actuated tone arm, apositioning and control mechanism comprising, in combination, a controlcam consisting of a single rotatable Wheel having one cam surface aroundits peripheral edge and a pair of additional coacting cam surfaces onits front and back faces respectively, with one of said cam surfacesincluding a spring section therein; a single cam follower plate mountedfor movement in at least two planes, with said plate adapted to beengaged by the peripheral edge of said wheel; a pair of cam followerpins xedly spaced apart from each other and mounted on said plate, anddisposed on opposite sides of the peripheral edge of the control cam;said cam pins being adapted to alternatively engage the separate opposedcam surfaces on the front and back faces thereof, with one of said pinsbeing adapted to engage the spring section of the aforementioned cam;with mechanical connections between the follower plate and the tone armto swing said tone arm into predetermined angular positions by operationof said pins in timed sequence with the rais- 7 ngfzemd lowerng -fofvsaid tone atm Jay engagement'of said v-T'11'n1:|er vuam fwith thecamllower plate. 2,3523 3'1 2,370,875 References Cited in the le of thispatent 2,424,132 UNITED STATES PATENTS 5 2563553 Num'ber Name fDate12,216,1)29 Wright Sept.2'4, 1940 Number 4'2,309,352 @Een 1911.26, 1943617,883

'Name Date Leine June'27, 1944 Pressley Mar. 6, 1945 Alexandersson :July15, 1947 Lingebrik Aug. 7, 1951 FOREIGN `PATENTS 'Country Date GreatBritain Feb. 14, 1949

